Conventionally, there have been proposed various sideslip angle estimation devices in which a sideslip angle is estimated by an integral calculus operation utilizing vehicle speed, yaw rate, and lateral acceleration as parameters. A sideslip angle is also estimated or derived from a vehicle model whose input variable is a quantity of state of a vehicle. A final sideslip angle is estimated based on both of the sideslip angle estimated by the integral calculus operation and the sideslip angle estimated by the vehicle model. A time constant of the integral calculus operation is adjusted depending on the sideslip angle estimated by the vehicle model.
One such sideslip angle estimation device has been disclosed in Japanese Patent Provisional Publication No. 8-332934.